Iontophoretic delivery of drugs: Fundamentals, developments and biomedical applications

In vitro transdermal iontophoretic delivery of leuprolide under constant current application

Transdermal delivery of Leuprolide, a nonapeptide LHRH agonist, was studied using constant current iontophoresis to explore methods for improving iontophoretic efficiency and determine the feasibility of delivery of therapeutic doses of the drug. Universal buffer consisting of citrate, phosphate and borate was used to carry out in vitro permeation experiments with heat separated human epidermis at pH 4.5 and 7.2. In addition, the effect of substituting this buffer with a macromolecular electrolyte, polymaleic acid, on the drug flux and the transference number was studied. Current densities from 0.5 to 2.3 microA/cm2 were used requiring moderate potential differences between 60 and 420 mV to be applied thus limiting irreversible epidermal membrane alterations. The rather high electrical resistance of the epidermis of the order of 200 kohms cm2 was related to the sub-physiological electrolyte concentration. Resistance was continuously monitored to guarantee barrier integrity of the membrane. The permeation rate increased linearly with the current density for the universal buffer and was at pH 7.2 almost double that at pH 4.5 despite the greater ionic valence of the drug at pH 4.5 compared to pH 7.2; this being because of the opposite direction of the electroosmotic flow at the two pH values. Drug transference number at both pH values was approximately 0.5%. Replacement of the universal buffer with polymaleic acid yielded higher drug permeation rates and increased its transference number at comparable pH. Transference number, however, was still approximately 1% at the highest current density, showing that concomitant ions from added electrolyte or extracted from the skin and the electrodes accounted for 99% of the total current. Further, transference number of the drug with polymaleic acid appeared to increase with current density. The fluxes obtained for both electrolyte systems with the present experimental arrangement could be extrapolated to deliver therapeutically relevant doses of the drug.

A prospective, randomized study using transdermal electromotive administration of verapamil and dexamethasone for Peyronie's disease

PURPOSE

Uncontrolled studies with intraplaque electromotive administration of verapamil and dexamethasone have demonstrated objective improvements in Peyronie's disease. We performed a prospective controlled study to assess the efficacy of intraplaque electromotive verapamil/dexamethasone vs electromotive lidocaine.

MATERIALS AND METHODS

Patients with Peyronie's disease were randomized into a study group (47 patients) and a control group (49 patients). For each treatment session an electrode receptacle was sited over the plaque and filled with either 5 mg verapamil and 8 mg dexamethasone (study group) or 2% lidocaine (control group), and a 2.4 mA electric current was applied for 20 minutes. All patients were scheduled for 4 sessions per week for 6 weeks. Assessment before and after treatment included measurements of plaque volume and penile curvature, and pain on erection (from questionnaire).

RESULTS

A total of 37 patients in the study group and 36 in the control group completed treatment courses. In the study group there were significant decreases in median plaque volume from 824 to 348 mm, and in penile curvature from 43 to 21 degrees. In the control group median volume and curvature were unchanged. The difference in results after treatment between the 2 groups was also significant. Significant pain relief occurred in both groups, transient in the control group and permanent in the study group. All patients experienced temporary erythema at the electrode site. There were no other side effects.

CONCLUSIONS

Intraplaque electromotive verapamil and dexamethasone induce substantial objective improvement in Peyronie's disease compared to electromotive lidocaine administration.

Investigation into the potential of iontophoresis facilitated delivery of ketorolac

The potential for iontophoresis facilitated transdermal transport of ketorolac was investigated using rat skin. Studies of electrical, physicochemical and device-related factors acting on the permeation kinetics of in vitro iontophoresis were performed. Iontophoresis increased the transdermal permeation flux of ketorolac as compared to the diffusion. Increase in applied current density or decrease in ionic strength of the donor solution enhanced the flux of the drug. Use of either platinum or silver/silver chloride electrodes resulted in similar enhancement of drug flux. Continuous current was more potent than pulsed current in promoting ketorolac transdermal permeation. Increasing the frequency or on:off ratio of pulse current induced an enhancement of the flux through the skin. An increase in donor drug loading dose or increasing the duration of current application resulted in enhancement of the drug flux. Pretreatment of the skin with D-limonene in ethanol or D-limonene in ethanol + ultrasound significantly enhanced the iontophoretic flux of the drug in comparison to passive flux with or without pretreatment. Trimodality treatment comprising of pretreatment with D-limonene in ethanol + ultrasound in combination followed by iontophoresis was found to be most potent for enhancing the rate of permeation of ketorolac.

Tolerance of ocular iontophoresis in healthy volunteers

To evaluate ocular tolerance, healthy volunteers were iontophoresed transclerally using novel OcuPhor trade mark hydrogel drug delivery applicators filled with balanced salt solution. In this three-period crossover study in 24 male and female subjects, 16 subjects received 0 mA and two of the following DC currents: 0.1, 0.5., 1.0, 2.0, 3.0, or 4.0 mA for 20 min; 6 subjects received 3 mA for 20 min and 1.5 mA for 40 min (both equivalent to 60 mAmin total charge). Safety and tolerance were determined by subjective VAS and objective ophthalmic assessments. Subjects were evaluated before and up to 22 hr after dosing. The applicators were well-tolerated and no clinically significant changes in symptomology or in ophthalmic assessments were seen following exposure to 0-3.0 mA for 20 min or 1.5 mA for 40 min. At 4.0 mA 2 of 4 subjects reported a burning sensation under the applicator during dosing which resolved by 22 hr post-dose; superficial changes in fluorescein staining were observed at 1 hr, but not at 22 hr. The OcuPhor trade mark system has promise for noninvasive drug delivery to the eye.

Failure to detect dexamethasone phosphate in the local venous blood postcathodic lontophoresis in humans

STUDY DESIGN

A single-blind, 2-factor (4 treatments by 8 time points) repeated-measures study design.

OBJECTIVE

To analytically determine dexamethasone and dexamethasone phosphate concentrations in plasma derived from proximal effluent venous blood, following cathodic iontophoresis.

METHODS AND MEASURES

Six volunteers received the following dexamethasone phosphate (2.5 ml, 4 mg/ml) treatments to their wrists on separate occasions: cathodic iontophoresis (4 mA, 10 minutes or 4 mA, 20 minutes), passive application (10 or 20 minutes). Plasma samples from the ipsilateral antecubital vein were obtained 10 minutes prior to and half way through the treatment (5 or 10 minutes), at the end of the treatment (10 or 20 minutes), and posttreatment (15, 30, 60, 90, and 120 minutes). The present investigation examined: (1) the sensitivity and linearity of extraction and analysis of dexamethasone and dexamethasone phosphate; (2) the necessity for determining both; and (3) the plasma levels from proximal effluent venous blood following cathodic iontophoresis.

RESULTS

The aggregate (n = 18) of the 6-point standard curves were linear for dexamethasone (r > 0.974) and dexamethasone phosphate (r > 0.829). In vitro dephosphorylation of dexamethasone phosphate to dexamethasone occurred in plasma at 37 degrees C and during freeze-thaw. Measurable dexamethasone or dexamethasone phosphate concentrations were absent at all time points and under all conditions in the human subjects.

CONCLUSIONS

These results demonstrate the sensitivity of the current assay and the need for evaluating both forms of the drug, as in vitro dephosphorylation results in the presence of dexamethasone and dexamethasone phosphate in samples. Absence of measurable dexamethasone or dexamethasone phosphate in the proximal effluent venous blood may require re-evaluation of the extent of drug delivery during the clinical iontophoresis of dexamethasone phosphate.

Transdermal administration of salmon calcitonin by pulse depolarization-iontophoresis in rats

Using the pulse depolarization-iontophoresis (PDP-IP) system, salmon calcitonin (sCT), a drug for the treatment of osteoporosis, was transdermaly administered in rats. While absorption of sCT was not observed after passive transdermal administration, the serum sCT concentration was confirmed at a dose of 0.2-4 microg when the PDP-IP system was employed. The results indicated that PDP-IP could enhance transdermal absorption of peptide drugs. Also noted was the increased amount of absorption of sCT along with an increase in the dose. We investigated the influence of electrical parameters (current, frequency) in PDP-IP on the transdermal absorption of sCT. An optimal current for drug absorption was found within the range of transported current (0.1-1.0 mA) employed for PDP-IP. In comparison with the results obtained at 0.1 mA, the drug absorption increased, along with an increase in transported current, when the current was set at 0.5 mA, while the drug absorption decreased at 1.0 mA in comparison. The decrease in drug absorption was assumed to be attributable to the structural destruction of skin by application of excessive current. There was no change in skin resistance attributable to the frequency; nor was there any influence of the frequency on the amount of drug absorption.

Diffusive transport properties of some local anesthetics applicable for iontophoretic formulation of the drugs

As part of a general study to improve the iontophoretic delivery of local anaesthetics of the amide type, the diffusion properties of the hydrochloride salts of bupivacaine, etidocaine, lidocaine, mepivacaine, prilocaine and ropivacaine, were studied in a 1% w/w agarose hydrogel. A source drug solution (25 mM) was placed in contact with the gel and, after an appropriate time, the drug concentration profile in the gel was analyzed to give a diffusion coefficient, D. The values of Dx10(10) expressed in m(2) s(-1) were: (bupi) 6.71, (eti) 6.71, (ropi) 6.39, (mepi) 7.31, (lido) 7.49 and (prilo) 7.76. For comparative reasons, the diffusion coefficient for LidHCl in an aqueous solution according to the Nernst-Hartley relation for the diffusion of ion-pairs was calculated, hereby taking into account ionic activity of LidH+ and Cl-. The diffusion coefficient thus obtained was 7.76x10(-10) m2 s-1 at infinite dilution. The relationship between the molecular weight of the compounds and the diffusion coefficient was investigated.

Responsive polymeric delivery systems

This paper discusses the state of the art in a relatively new approach in the field of controlled drug delivery-responsive polymeric drug delivery systems. Such systems are capable of adjusting drug release rates in response to a physiological need. The fundamental principles of externally and self-regulated delivery systems are examined. Special attention is paid to specific clinical settings such as diabetes, presenting the advantages and disadvantages of different approaches.

In vitro iontophoretic release of lithium chloride and lidocaine hydrochloride from polymer electrolytes

Ionically conducting polymers, frequently known as polymer electrolytes, are potential candidates as hosts for drugs to be delivered iontophoretically. The iontophoretic delivery of lithium or lidocaine from polymer electrolyte films through a cellophane membrane was examined using different delivery current regimes. Thin, mechanically strong, polymer electrolyte films were fabricated from poly(ethylene oxide) (PEO) with lithium chloride or lidocaine hydrochloride. Experiments showed that iontophoretic transport of both lithium chloride and lidocaine hydrochloride might be achieved from these PEO-based films. Cation transport number determinations give values for PEO-based films of about 0.4 for lithium chloride systems and 0.12 for lidocaine hydrochloride systems. The mechanism of transport from these PEO-based polymer electrolyte films allows the delivery of ionic salts such as lithium chloride and lidocaine hydrochloride to be controlled solely by current, thus providing a system that can deliver precise amounts of drug.

Transdermal iontophoresis revisited

Iontophoresis evolved as a transdermal enhancement technique in the 20th century, primarily for the delivery of large and charged molecules. Significant achievements have been made in the understanding of underlying mechanisms of iontophoresis and these have contributed to the rational development of iontophoretic delivery systems. The major challenges in this area are the development of portable, cost effective devices and suitable semi-solid formulations that are compatible with the device and the skin. Some of the obstacles in transdermal iontophoresis can be overcome by combining iontophoresis with other physical and chemical enhancement techniques for the delivery of macromolecules. Iontophoresis also offers an avenue for extracting information from the body through the use of reverse iontophoresis, which has potential application in diagnosis and monitoring. The current research is focussed towards resolving the skin toxicity issues and other problems in order to make this technology a commercial reality.

The effect of electroporation on iontophoretic transdermal delivery of calcium regulating hormones

Electrically-assisted delivery by iontophoresis and/or electroporation was used in vitro to deliver the calcium regulating hormones, salmon calcitonin (sCT) and parathyroid hormone (1-34) (PTH) through human epidermis. Such delivery could be useful for chronic treatment of post-menopausal osteoporosis and other clinical indications as a superior alternative to parenteral delivery. sCT (50 microg/ml) or PTH (1-34) (100 microg/ml) formulation was prepared in citrate buffer (pH 4.0 or 5.0, respectively). Epidermis separated from human cadaver skin was used. Iontophoresis was applied using a constant current power source and electroporation with an exponential pulse generator. Silver/silver chloride electrodes were used. A combination of electroporation and iontophoresis resulted in higher transdermal permeation than either one technique alone. Electroporation also shortened the lag time of iontophoretic transdermal delivery of salmon calcitonin. Pulsing at lower voltages followed by iontophoresis did not result in increased transport (over iontophoresis alone), perhaps because the transdermal voltage was very low. The transdermal transport of salmon calcitonin by pulsing with 15 pulses (1 ppm) of 500 V (200 ms) followed by iontophoresis led to a quick input and high flux. The average transdermal voltage was only about 50 V for a 500 V study.

An in vivo investigation of the rabbit skin responses to transdermal iontophoresis

To optimize the benefits of transdermal iontophoresis, it is necessary to develop a suitable animal model that would allow for extensive assessments of the biological effects associated with electro-transport. Rabbit skin responses to iontophoresis treatments were evaluated by visual scoring and by non-invasive bioengineering parameters and compared with available human data. In the current density range 0.1-1.0 mA/cm(2) applied for 1 h using 0.9% w/v NaCl and 0.5 mA/cm(2) for up to 4 h, no significant irritation was observed. 2 mA/cm(2) applied through an area of 1 cm(2) for 1 h resulted in slight erythema at both active electrode sites but without significant changes in transepidermal water loss (TEWL) and laser Doppler velocimetry (LDV). A value of 4 mA/cm(2) under similar conditions caused moderate erythema at the anode and cathode with TEWL and LDV being significantly elevated at both sites; 1 mA/cm(2) current applied for 4 h, caused moderate erythema at both anode and cathode; and 1 mA/cm(2) applied for 1 h caused no irritation when the area of exposure was increased from 1 to 4.5 cm(2). When significant irritation and barrier impairment occurred, the erythema was resolved within 24 h with barrier recovery complete 3-5 days post-treatment. Rabbit skin thus shows promise as an acceptable model for iontophoresis experiments.

Gelatin-stabilised microemulsion-based organogels: rheology and application in iontophoretic transdermal drug delivery

Gelatin-containing microemulsion-based organogels (MBGs) have been formulated using pharmaceutically acceptable surfactants and oils such as Tween 85 and isopropyl myristate. MBG formulations were subject to rheological study and their utility in transdermal drug delivery examined. Unlike most organogels, MBGs are electrically conducting and have been successfully employed in this study for the iontophoretic delivery of a model drug through excised pig skin. Iontophoresis using MBGs gave substantially higher release rates for sodium salicylate compared to passive diffusion, and fluxes were proportional to the drug loading and the current density. MBGs provide a convenient means of immobilising the drug and are rheologically similar to their hydrogel counterparts at comparable gelatin concentrations. MBGs also appear to offer improved microbial resistance in comparison to aqueous solution or hydrogels.

Iontophoretic transdermal delivery of salicylic acid dissolved in ethanol-water mixture in rats

The usefulness of iontophoresis is restricted to highly water-soluble compounds, since drugs are generally applied as an aqueous solution in a drug electrode. In the present study, salicylic acid (SA) dissolved in ethanol-water mixture was loaded in a drug electrode, and the effect of ethanol on the iontophoretic transdermal delivery of SA was evaluated. Ethanol at a concentration of 10 or 30% showed no significant effect on the iontophoretic transdermal delivery of SA compared to that in the absence of ethanol, but 40 or 70% ethanol increased it significantly. The current density passing through in vivo during iontophoretic treatment decreased with increase in ethanol concentrations. These results suggested that the enhanced transdermal absorption of SA iontophoretically by the presence of ethanol in a drug solution is not due to the increased current density in vivo, but probably due to the direct action of ethanol on the stratum corneum. In conclusion, addition of ethanol to a drug solution at an appropriate concentration was proved to enhance the iontophoretic transdermal delivery of SA. A mixture of ethanol and water can dissolve many poorly water-soluble drugs, and therefore it would be able to expand the application of iontophoresis to include many drugs that are poorly soluble in water.

An analysis of solute structure-human epidermal transport relationships in epidermal iontophoresis using the ionic mobility: pore model

This study sought to examine the extent the ionic mobility-pore model, used to describe epidermal iontophoretic structure-permeability relationships, could describe a range of published iontophoretic data. The model incorporates, as determinants of iontophoretic transport, solute size, solute mobility, total current applied, presence of extraneous ions, determined by conductivities of both donor and receptor solutions, permselectivity of the epidermis, as well as a solute pore interaction term which together provided an excellent regression for iontophoretic permeability. The 'pore' radii for solute transport estimated from literature iontophoretic permeabilities using the model ranged from 6.8 to 17 A depending on the degree of hydration and conformation of solute assumed. The pore size range is consistent with transport through the polar intercellular and transappendageal pathway for transport. The pore restriction form of the model better describes the data obtained to date than other models described previously (Yoshida, N.H., Roberts, M.S., Solute molecular size and transdermal iontophoresis across excised human skin. J. Control. Release 25 (1993) 177-195).

Physical characterization of polymer electrolytes as novel iontophoretic drug delivery devices

Polymer electrolytes are solid-like materials formed by dispersing a salt at the molecular level in a high molecular weight polymer such as poly(ethylene oxide) (PEO). They have been extensively studied for use in electrochemical applications such as batteries and display devices. This paper considers a novel application of polymer electrolytes as the basis of iontophoretic drug delivery systems. Polymer electrolyte films were cast from solutions of PEO and various drug salts using either water or an acetonitrile/ethanol mixture as the solvent. These films were characterized by variable-temperature polarizing microscopy (VTPM), differential scanning calorimetry (DSC), and alternating current (AC) impedance analysis. The films were around 100-micron thick and mechanically strong; the optical and thermal methods provided evidence that the polymer electrolytes had crystalline and amorphous phases, although some drugs may exist in films as nanodispersions. The amorphous phase is important as ions have greater mobility in this phase and therefore allow a current to be passed when the material is incorporated into a device such as one suitable for drug delivery by iontophoresis. The AC impedance analysis showed that the conductivity of the films varied between 10(-6) and 10(-3) S cm-1, depending on the salt, casting solvent, and temperature. Two drugs in particular were shown to be promising candidates in these systems: lidocaine hydrochloride and lithium chloride.

Transdermal iontophoretic delivery of methylphenidate HCl in vitro

Methylphenidate is prescribed orally for Attention Deficit Disorder in children and adults, and for narcolepsy patients. Methylphenidate has a short plasma half-life (1-2 h) and thus needs to be frequently administered for effective therapy. Such therapy has limitations in terms of patient compliance, particularly in young children. For such reasons, the development of a transdermal dosage form of methylphenidate may be useful. This study was undertaken to evaluate the passive and electrically assisted transport (iontophoresis) of methylphenidate from aqueous methylphenidate hydrochloride solutions across excised human skin. A maximum flux of 12.0 micrograms/(cm2 h) of protonated methylphenidate was estimated from the passive transport data at pH 3.5. Iontophoresis significantly enhanced protonated methylphenidate transport as compared with passive delivery. From the present experiments, the efficiency of iontophoretic delivery of methylphenidate was approximately 700 micrograms/(mA h). Based on in vitro skin flux data, the daily dose of 15-40 mg methylphenidate can be achieved using a current density of 0.5 mA/cm2 and a minimum transport area of 2-5 cm2 for 24-h application, or an area of 4-10 cm2 for 12-h (daytime) application. From methylphenidate skin flux values, methylphenidate mobility of 2.2 x 10(-4) cm2/(V s) was estimated, which compares reasonably with its free solution mobility of 6.6 x 10(-4) cm2/(V s).

Transdermal alniditan delivery by skin electroporation

The aim of this study was to evaluate the transdermal permeation of alniditan by electroporation and to compare with iontophoretic delivery. The influence of the electrical parameters of electroporation was investigated in vitro using a factorial design study. The transdermal flux of alniditan was enhanced by two orders of magnitude by application of high voltage electrical pulses. The electrical parameters of electroporation-i.e. the voltage, the duration and the number of pulses-allowed a control of drug permeation. Both transport during and after pulsing were shown to be important for alniditan transdermal delivery by electroporation. Electroporation was found more efficient in promoting alniditan permeation than an iontophoresis transferring the same amount of charges.

Different indentation velocities activate different populations of mechanoreceptors in humans

We have examined whether different skin machanoreceptors are activated by different indentation velocities of a tactile probe. Indentations of 300 microns at velocities of 100 and 400 microns/ms were applied at the dorsolateral side of the foot and at the tip of digit III. Compound sensory action potentials (CSAPs) were recorded from the sural and median nerves, respectively. The amplitudes of the tactile CSAPs were < 1-2 muV, and less than 15% of the CSAPs evoked by electrical stimulation. The areas of the polyphasic tactile CSAPs were 35-38% smaller at 100 microns/ms than at 400 microns/ms. The maximal sensory nerve conduction velocities (SNCVs) were higher in the median than in the sural nerves. In both nerves, the SNCVs were similar at electrical and 400-micron/ms tactile stimulation but 11-17% lower at 100-micron/ms stimulation. Cocaine hydrochloride was applied iontophoretically at the dorsolateral side of the foot, causing a decrease of 50% of the CSAP evoked by 100 microns/ms but only 14% at 400 microns/ms. These studies suggested that identation at 400 microns/ms activated mainly deeply placed (Pacini corpuscles) and to some extent superficial mechanoreceptors, whereas the 100-micron/ms indentation activated primarily superficially situated receptors (Meissner corpuscles, and some slowly adapting units).

Lidocaine iontophoresis for topical anesthesia before intravenous line placement in children

In a double-blind randomized trial including 42 children aged 7 to 18 years, less pain occurred with intravenous placement after iontophoresis of 2% lidocaine with epinephrine, as reported by patients (p = 0.005), parents (p = 0.001), intravenous personnel (p = 0.009), and investigators (p = 0.0002) compared with placebo therapy. Lidocaine iontophoresis provides rapid and effective topical anesthesia for intravenous access in children.

Electromotive drug administration of lidocaine to anesthetize the bladder before intravesical capsaicin

PURPOSE

The discomfort caused by intravesical capsaicin during instillation may restrict its use in some patients. We studied the effectiveness of using electromotive drug administration (EMDA) of lidocaine to anesthetize the bladder before capsaicin.

MATERIALS AND METHODS

EMDA of lidocaine and epinephrine was performed in 8 patients with detrusor hyperreflexia using catheters, electrodes and an electrical current generator (20 mA., 15 minutes) followed immediately by intravesical capsaicin (2 mmol./l.) for 30 minutes under urodynamic monitoring. The patients scored suprapubic pain at 5 minutes and at the end of the capsaicin instillations on a scale of 0 to 10. Of the 8 patients 5 had had previous capsaicin treatments and the scores were compared to previous scores when intravesical lidocaine without EMDA had been used as local anesthesia before capsaicin.

RESULTS

The pain scores during capsaicin instillations after EMDA of lidocaine were much lower than those during capsaicin instillations after lidocaine alone. EMDA virtually eliminated the hyperreflexic contractions of the bladder occurring during capsaicin instillations, thus reducing the risk of urethral leakage, and prevented autonomic dysreflexia that had previously occurred in 1 patient.

CONCLUSIONS

EMDA of lidocaine is an effective means of reducing pain during subsequent intravesical capsaicin, which makes the use of capsaicin in the treatment of detrusor hyperreflexia more acceptable.

Transdermal iontophoretic delivery of hydrocortisone from cyclodextrin solutions

Enhanced skin penetration of hydrocortisone can be desirable for treatment of several diseases. Transdermal iontophoretic delivery of hydrocortisone solubilized in an aqueous solution of hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) was investigated and compared with chemical enhancement of co-solvent formulations. The passive permeation of hydrocortisone through human cadaver skin was higher when delivered from propylene glycol than when delivered after solubilization in an aqueous solution of HP-beta-CyD. However, the iontophoretic delivery of the 1% hydrocortisone-9% HP-beta-CyD solution was higher than the amount delivered passively by the 1% hydrocortisone-propylene glycol formulation, even if oleic acid was used as a chemical enhancer. Iontophoretic delivery of 1% hydrocortisone with 3% or 15% HP-beta-CyD was lower than that of the 9% HP-beta-CyD solution. These data suggest that free hydrocortisone rather than complexes is predominantly delivered iontophoretically through the skin and the HP-beta-CyD complex serves as a carrier to replenish depletion of hydrocortisone. HP-beta-CyD prevents hydrocortisone from forming a skin reservoir. Iontophoresis provides better enhancement of transdermal delivery of hydrocortisone than the chemical approach when just sufficient HP-beta-CyD is added to solubilize the hydrocortisone.

Intravesical electromotive administration of drugs for treatment of superficial bladder cancer: a comparative Phase II study

OBJECTIVES

To evaluate the efficacy of electromotive administration (EMDA) of intravesical mitomycin-C (MMC) in patients with superficial bladder tumors and to evaluate the toxicity of the treatment.

METHODS

Thirteen patients with multifocal Stages Ta-T1 and G1-G2 transitional cell carcinoma (TCC) of the bladder, primary or recurrent (group A), received MMC 40 mg (retained in the bladder for 2 hours) once a week for 8 weeks. Fifteen patients with the same characteristics (group B) were treated with EMDA/MMC at a current of 15 mA for 20 minutes once a week for 8 weeks. All lesions in the bladder except one (marker) were resected in each patient.

RESULTS

In group A, 5 of 12 patients (41.6%) demonstrated complete macroscopic and histologic disappearance of the marker lesion (complete response [CR]). In group B, 6 of 15 patients (40%) had a similar CR. Recurrence rate in responders was 60% in group A versus 33% in group B after 7.6 and 6 months, respectively. Disease-free interval was 14.5 months in the EMDA/MMC group compared to 10.5 months in the MMC group. Side effects were few.

CONCLUSIONS

In intermediate risk patients with TCC of the bladder, EMDA/MMC was not superior to MMC alone with a CR rate of 41% versus 41.6%. In responders, a lower recurrence rate and a longer disease-free interval were observed in the EMDA/MMC group.

Electromotive administration of oxybutynin into the human bladder wall

PURPOSE

To compare concentrations of oxybutynin in the human bladder wall after either passive delivery (PD) or electromotive administration (EMDA).

MATERIALS AND METHODS

Tissue sections of human bladder were inserted into a diffusion cell with urothelium exposed to the donor compartment containing oxybutynin (4.5 mg. in 100 ml. NaCl 0.45%) and an anode. Twelve paired experiments, "current 5 mA/no current", were conducted over 15 minutes. Oxybutynin tissue contents were measured and tissue viability, morphology and oxybutynin stability were assessed.

RESULTS

Mean oxybutynin tissue concentrations were 3.84 micrograms./gm. in samples exposed to EMDA and 0.87 microgram./gm. in samples exposed to PD (p = 0.0006). The mean coefficients of variation were 57.85% in EMDA experiments and 89.78% in PD experiments. Tissues were viable and undamaged histologically and no oxybutynin structural modification was observed.

CONCLUSIONS

EMDA enhances oxybutynin administration into viable bladder wall and reduces the variability in drug delivery rate.

Treatment of keloid and hypertrophic scars by iontophoretic transdermal delivery of tranilast

The feasibility of iontophoretic transdermal delivery of tranilast (N-(3,4-dimethoxycinnamoyl) anthranilic acid) for the treatment of keloid and hypertrophic scars was evaluated in hairless rats and humans. A drug electrode containing tranilast 1.5 ml (8 mg/ml in ethanol/water (8/2, v/v) mixture) was placed on the dorsal skin surface of anaesthetised rats or the affected parts of patients, and connected to the negative pole; an electric current (0.5-4 mA for rats, 2 mA for people) was pulsed through at one minute intervals. Tranilast was effectively delivered transdermally iontophoretically into the restricted skin tissues of hairless rats and the affected parts of four patients with hypertrophic scars with no skin damage. In four other patients tranilast given iontophoretically for a period of 30 minutes a week reduced the patients' complaints of pain and itching after only one or two treatments although there were some variations among patients. These results indicate that the transdermal iontophoretic delivery of tranilast is a useful treatment for keloid and hypertrophic scars, particularly for relieving pain and itching, and is more beneficial than tranilast given orally.

Delivery of medication by iontophoresis to treat post-burn hypertrophic scars: investigation of a new electronic technique

At present, direct current (DC) and pulsed direct current (PDC) methods are used for iontophoresis. Although the DC field has high efficiency, it exhibits some side-effects. The PDC field has little side-effects, but the efficiency is lower. In this study, a new iontophoretic drug device was designed for providing the maximal efficiency with the minimal side-effects. Tests of animal and human models showed that the permeation rate of the new field was higher than that of PDC and DC fields, and side-effects were lower than that of the DC field.

Comparison of electromotive drug administration with ketorolac or with placebo in patients with pain from rheumatic disease: a double-masked study

This study was undertaken to assess the efficacy of ketorolac compared with placebo when delivered by electromotive drug administration (EMDA) in patients with pain from rheumatic disease. In EMDA, or iontophoresis, a low-intensity electric current is applied over the skin to deliver medication into body tissues. Although EMDA has been used to treat patients with various diseases, controlled studies are lacking in patients with rheumatic disease. This double-masked study included 60 patients (43 women and 17 men) aged 31 to 80 years with the following conditions: 12, epicondylitis; 30, scapulohumeral periarthritis; 10, gonalgia; and 8, metatarsalgia. They were divided randomly by a physician into 2 groups of 30 patients each for 5 sessions of active treatment (30 mg of ketorolac) or placebo (5 mL of normal saline). Treatment took place every other day for 20 minutes. Immediately before and after the five treatment sessions and 7 days after treatment ended, both patient and physician measured the degree of pain using a categoric scale (no pain, slight pain, intermediate pain, strong pain, and very strong pain) and evaluated pain intensity using the Scott and Huskisson Visual Analogue Scale (VAS). Seven days after treatment ended, both physician and patient judged the result of treatment using a second categoric scale (no improvement or intermediate, good, or very good result). Both ketorolac and placebo provided immediate, significant pain relief when delivered by EMDA, but only those patients receiving ketorolac experienced a further reduction in pain 7 days after treatment; those receiving placebo experienced a slight increase in pain. VAS values differed significantly between the two groups. Poor results (no improvement) were significantly higher in the placebo-treated group, while good results were significantly higher in the ketorolac-treated group. No patient reported any adverse effects during treatment. This study demonstrates that ketorolac relieves pain when delivered by EMDA and offers longer-lasting pain relief than does placebo.

Effects of phospholipids on the in vitro percutaneous penetration of prednisolone and analysis of mechanism by using attenuated total reflectance-Fourier transform infrared spectroscopy

We investigated the effects of 10 phospholipids on the in vitro percutaneous penetration of prednisolone (PR) through the dorsal skin of guinea pigs. A marked enhancing effect of PR penetration was observed in the presence of phospholipids that have unsaturated acyl chains. A maximum of 68-fold enhancement was observed compared to that of control. On the contrary, phospholipids that have saturated acyl chains did not significantly increase the amount of PR passing to the receptor side. Attenuated total reflectance-Fourier transform infrared spectroscopy was used to monitor the outer several microns of stratum corneum (SC) surface. It was observed that phospholipids that have unsaturated acyl chains induced higher and broader absorbance shifts in the C-H bond stretching region while phospholipids that have saturated acyl chains induced lower and sharper absorbance shifts in the C-H bond stretching region. A significant parallel between the amount of PR penetrated and the lipid-chain fluidity of the SC was found. These results suggest that phospholipids may influence the percutaneous penetration of PR by changing the lipid-chain fluidity of the SC.

Multiple emulsion-based systems carrying insulin: development and characterization

An insulin delivery system based on liquid surfactant membranes has been developed. The formulation was based on a w/o/w emulsion where an organic membrane separated two aqueous phases and the internal aqueous phase contained insulin. Sesame and cotton seed oils were used as organic membranes. In order to facilitate the transportation of glucose across the organic membrane various additives such as calcium stearate, lecithin, cholesterol, hexamine, stearic acid and glyceryl tristearate were used. The additives were found to be successful carriers for the transportation of glucose to the internal aqueous phase. Similarly, viscosity enhancers, e.g. cetostearyl alcohol, in the organic phase enhanced the immobilization of insulin. Various parameters affecting the stability of the emulsions were established. The developed system was characterized for insulin activity and insulin efflux profile.

Portable current stimulator for transdermal iontophoretic drug delivery

A pulse stimulator was designed. It is small sized (3 x 2 cm printed circuit board) and battery-powered (185 microA total static current). The current intensity and pulse duration of this device can be continuously varied. Preliminary trials of lidocaine show that this device is usable for transdermal drug delivery and may be valuable for portable applications.